Field of the Invention
The present invention relates to a device for torsion-proof cnnnection of a number of elements in direct or indirect rolling contact with each other, which together make a robot arm or the like, where the elements are held together and can be moved by force transmitting actuators, for example cords.
In the Swedish Pat. Nos. 7902366-9 and 8001998-7, which correspond in part to U.S. Pat. No. 4,393,728, a robot arm is described which is especially characterized by having a great flexibility in different planes, whereby its ability to get around barriers is great. It can thus be inserted in curved or angled spaces, which previously was almost impossible. The great flexibility of the robot arm is achieved because the arm consists of a larger number of disc-like elements which have a rolling contact with each other.
An absolute requirement for robot arms of this type is that in addition to a relatively large weight bearing capability at the free end of the arm it be possible to transmit torques and maintain large torsional moments. The relatively poor torsional resistance of cord maneuvered robot arms, which is caused by the rounded form of the individual elements, has indeed been improved through providing the rolling surfaces of the elements with teeth or the like, which engage each other, but in many cases another torsion locking of the elements is desirable.